1. Technical Field of the Invention
This invention most generally relates to apparatus and methods of catheterization and related treatments of the genitourinary and gastrointestinal passages of mammals. More particularly, the invention relates to catheters, dilators, occluders, stents, suprapubic catheters, camera introducers and related medical devices subject to being proximally propelled and directed for advancement and control in mammalian genitourinary and gastrointestinal passages.
2. Description of the Prior Art
In most mammals, mucous membranes line all those passages by which the internal parts communicate with the exterior, and are continuous with the skin at the various orifices of the surface of the body. They are soft and velvety, and very vascular, and their surface is coated over by their secretion, mucus, which is of a tenacious consistence, and serves to protect them from the foreign substances introduced into the body with which they are brought in contact.
They are described as lining the two tracts—the genitourinary and the gastrointestinal; and all, or almost all, mucous membranes may be classed as belonging to and continuous with the one or the other of these tracts. Catheterization of any of these similar bodily passages may at times be useful or necessary.
Urinary outlet problems most likely have been around for as long as humans. History has the ancient Chinese using onion stalks to relieve people of acute urinary retention. Literature refers to such problems as far back as 206 B.C., more than 2000 years ago. Romans used catheters, first invented by Erasistratus, a Greek doctor in the third century B.C. Roman catheters were fine tubes made of bronze. The Roman gynecologist Soranus describes how catheters could be used to push stones out of the way and back into the cavity of the bladder, and thus restore urine flow. Excavations in Pompeii unearthed several bronze catheters. These instruments were well constructed but relatively simple and showed that designs changed little from the period 79 AD until 1700 A.D.
However, during the 17th and 18th centuries catheter construction became more complex with an intensified search for an appropriate substance that would be at once flexible, non-irritating and functional. England, France, and the U.S.A. had individuals and companies deeply involved with urinary catheters during this period. Many variations were produced but they all caused much stress on the patient when these rigid devices were pushed into the urethra. The first practical breakthrough was by the French using gum elastic catheters—a catheter that would bend better in the urethral channel and not scour the mucosa so much in the process.
Charles Goodyear improved upon what the French produced when he successfully vulcanized crude rubber. The problem of manufacturing an instrument which was both sufficiently rigid to enable it to be pushed through the urethra into the bladder and yet flexible enough to negotiate the path, had at last reached the point of practicality, not withstanding its shortcomings. At that time, and still to this day, a functional urethral catheter is defined as one that is flexible enough to negotiate the bends and stable enough to push through the length of the urethral passage.
The French urologist J. J. Cazenave, with the hopes that his country would regain leadership in the catheter field, dedicated 25-30 years of his life improving the flexible durable catheter. This was in the late 1800's and his catheter, made of decalcified ivory, was a dated device but shows the consistency of the state of the art wherein catheters are pushed into and negotiated along the urethral passage toward the bladder.
During the past 300 years or so, intensified development efforts were stimulated by professional pride, national pride and financial rewards. These efforts yielded many improvements, such as changes to size, curve shape, materials of construction, smoothness, lubricants, coatings, combinations of materials, physical properties, chemical properties and more, yet all subscribed to the basic principle of external push-to-advance.
The catheters of the prior art are large and stiff, difficult and uncomfortable to administer, and uncomfortable to wear for extended periods. There is a degree of skill, tolerance and patience required that takes much time, training and practice to learn. The difficulty, discomfort, risk of injury and infection, inhibition and inconvenience of the methods and tools of the known art results in the deprivation for many patients of the freedom to work, play and travel as do unaffected people.
The anatomy of the adult male urinary tract, as illustrated in FIG. 1, has a bladder 004 where urine is collected prior to exiting the body via the urethra 006. The bladder 004 converges into the urethra 006 at a muscular exit called the bladder neck 005. Approximately the first one inch of the urethra lies within the prostate 007, which is a chestnut-sized gland. The next approximately half inch passes through the external sphincter 008, which is the muscular flow valve that controls the release of urine. The remaining six inches of the urethra lie in a spongy zone, exiting the body at the meatus 009.
The normal process of emptying the bladder can be interrupted by two causes. One is bladder outlet obstruction and the other is failure of the nerves linking the bladder to the brain. The most frequent cause of bladder outlet obstruction in males is enlargement of the prostate gland by hypertrophy or hyperplasia. In older males, it is not uncommon for a progressive enlargement of the prostate to constrict the prostate urethra. This condition, known as benign prostatic hyperplasia (BPH), can cause a variety of obstructive symptoms, including urinary hesitancy, straining to void, decreased size and force of the urinary stream and in extreme cases, complete urinary retention possibly leading to renal failure.
The most common surgical intervention for BPH, transurethral resection of the prostate, or TURP, has a lengthy recovery period of up to one year, and presents a high operative risk for complications such as sexual dysfunction. Up to 10% of those subjected to such surgery are left with mild to moderate stress incontinence. Approximately 400,000 patients in the United States and approximately 500,000 patients internationally were diagnosed in 1994 with BPH or cancer-induced bladder outlet obstructions that were sufficiently severe to warrant TURP or alternative surgery, according to industry sources.
Because of the high costs, medical risks and quality of life compromises associated with TURP, new technologies have begun to challenge TURP's position as the standard treatment for severe BPH. Recently, the U.S. Food and Drug Administration approved two drugs, tera zosin hydrochloride and rinasteride, to treat BPH. These drugs generally do not improve symptoms for six to nine months after treatment begins, and are not without side effects.
Urethral strictures are another cause of outlet obstruction, often due to fibrous tissue growth resulting from reaction to catheters or cystoscopes or from injury, birth defects or disease, and are commonly treated by urethral dilation, catheterization or surgery. Men with urethral strictures also experience a limited ability to urinate, which may cause extreme discomfort and, if left untreated may cause complications that necessitate catheterization. Approximately 50,000 patients in the United States were diagnosed with recurrent urethral strictures in 1994, according to industry sources. The inventor estimates that approximately 75,000 additional patients were diagnosed internationally.
Women suffer from urinary incontinence far more often than men and at an younger age primarily because of the stress associated with pregnancy and childbirth, the shorter length of the female urethra, and the absence of a prostate. The U.S. Department of Health and Human Services (HHS) estimates that the involuntary loss of urine affects approximately 10 million Americans of which 8.5 million are women. Seven million of these women are non-institutionalized, or community-dwelling.
For women between the ages of 15 and 64, the prevalence of urinary incontinence is estimated to range from 10 to 25 percent of the population. For non-institutionalized persons over the age of 60, the prevalence of urinary incontinence ranges from 15 to 30 percent, with the prevalence in women twice that of men.
The involuntary loss of urine can be caused by a variety of anatomical and physiological factors. The type and cause of urinary incontinence is important to how the condition is treated and managed. The two broad categories of urinary incontinence are urge and stress incontinence. Some people suffer from what is termed mixed incontinence or a combination of stress and urge incontinence.
Urge incontinence is the involuntary loss of urine associated with an abrupt and strong desire to void. In most cases, urge incontinence is caused by involuntary detrusor (the smooth muscle in the wall of the bladder) contractions or over-activity. For many people, urge incontinence can be satisfactorily managed with pharmaceuticals.
The more frequently occurring stress incontinence is the involuntary loss of urine caused by movement or activity that increases abdominal pressure. The most common cause of stress incontinence is hypermobility or significant displacement of the urethra and bladder neck during exertion. A less frequent cause of stress incontinence is intrinsic urethral sphincter deficiency (ISD), a condition in which the sphincter is unable to generate enough resistance to retain urine in the bladder.
Females, and males with no benign prostatic hyperplasia condition, might also have the inability to empty their bladder because of the nerves linking the bladder to the brain. This condition is known as neuropathic bladder, may occur in a wide variety of conditions which include spina bifida, multiple sclerosis, spinal injury, slipped disc and diabetes. When these and other problems prevent the bladder from effectively controlling urine there are a number of treatment options. They are catheters, dilators, occluders, and stents.
Indwelling Foley-Type Catheters
During continuous catheterization an indwelling catheter is retained in the bladder by a water filled balloon. It drains urine continuously from the bladder via a connecting tube into a bag which is attached to the leg or bed. The bag has a tap so that the urine can be emptied at intervals. The catheter is usually inserted by a doctor or nurse and changed about every four to six weeks. But difficulty in placement has always been inherent in this design. This is due to the traditional “push to advance” technology which necessitates a relatively stiff, thick-walled catheter to traverse the delicate mucosal lined urethra.
Often the French (unit of measurement) size of the catheter is dictated by the need for stiffness to insert rather than the lumen size to pass urine. A 14 French or smaller Foley is rarely used because catheters of this size lack the column strength needed to push the full length of the urethra into the bladder. The larger French Foley catheters are painful to place, uncomfortable when indwelling, and require a highly skilled care provider to insert.
Intermittent Catheters
During intermittent catheterization a simple catheter made of plastic, rubber, or metal is inserted by the patient or a helper for just long enough to empty the bladder completely, which is typically about one minute. These tubes are usually smaller in diameter and stiffer than an indwelling catheter of the same size. This stiffness can make catheterization difficult in men because the urethra is long and has an acute bend within the prostate. When the external sphincter is reached the sphincter muscle will contract making passage difficult. Most patients learn to catheterize themselves and thereby gain a large degree of independence. This process is repeated about every 3-4 hours during the day and occasionally as needed at night.
Intermittent catheterization is mainly used by people who are incontinent due to neuropathic bladder. Intermittent catheterization may also be utilized by people who cannot empty the bladder because the bladder muscle is weak and does not contract properly. In some patients, an alternate apparatus and method used to maintain long term drainage of the bladder is the use of a suprapubic tube.
Suprapubic Catheters
Suprapubic catheterization of the bladder is performed via transabdominal puncture which enters the body above the pubic arch and is directed into the bladder using ultrasound or fluoroscopy to guide the trocar introducer and suprapubic catheter. The needle introducer is then removed when proper catheter placement within the bladder is confirmed, leaving the drainage catheter in place.
Long term drainage may require the fixation of the catheter at the skin using standard adhesive based interface components to address mechanical fixation, inflection control, and skin compatibility. The distal end of the catheter is commonly contained within the bladder by inflated balloon, winged-shaped tip configurations which expand within the bladder, or pre-shaped curved catheter tips which curl to their original J-shape when stiffening wire is removed from the catheter lumen.
A problem with this form of distal end emplacement through the bladder wall is that it is only unidirectional; that is, it only resists the inadvertent pulling out of the tip of the catheter from the wall of the bladder, while allowing the catheter to freely pass further into the bladder, and back out up to the point of the containment structure. This continuing catheter motion in and out of the bladder puncture site may irritate tissue and cause infection or other difficulty at the bladder-catheter interface. Urine is especially irritating to most parts of the human body that are outside the urinary tract.
Dilators
Dilation is accomplished by pushing successively larger urethral dilation tubes through the urethra to increase the size of the lumen, a procedure which is painful and traumatic to the patient. Surgical treatment of strictures involves surgical risks as well as complications, including infection, bleeding and restenosis, which requires further treatment.
With the exception of balloon catheters, the current art of dilators has also changed little over the passage of time. A shaft with an increasing taper, bulbous structure, or enlarged end is pushed from without the passage to advance the tool through the restricted passage, thus forcing by longitudinally-applied pressure the lateral expansion of the passage walls. This push-to-advance method necessitates a stiff shaft which has all the same liabilities as traditional catheters. Catheters inherently provide a degree of this dilatorial function to the extent that the passage is opened sufficiently to accommodate the catheter.
Occluders
Occluders are used in some cases to control incontinence. Occluders of the prior art are constructed and applied with the same push-to-advance concept as catheters and dilators described above, with the same liabilities. The basic occluder is a bulb or plug on a shaft which is inserted within a passageway to stop or prevent the normal flow of materials through the passageway, or driven all the way into the bladder, for example, and allowed to seat as a plug at the neck of the urethra to prevent the flow of urine from the bladder.
Stents
A stent is a tubular metallic mesh device that is implanted to open and support a stricture to allow for urine flow. The stent body is between 3.5 cm and 6.5 cm in length depending on the anatomy, and is expandable by design to anchor in place. The stent being a mesh has openings that allow the tissue to grow through the wall making removal difficult and causing encrustation that reduces urine flow.
Intraurethral Valved Catheters
An intraurethral valved catheter is a device that is implanted to control the flow of urine with an integral valve that is remotely actuated. Since the entire catheter length is within the urethra, the chance for external infection is reduced. The anchoring mechanism of current designs is accomplished with balloons, or “petal like” projections from the catheter. Both designs are complicated to install and difficult to remove, and if the valve fails, leaves the patient in a painful and dangerous situation.
Patents in the Prior Art
There has been patent activity in the prior art indicating dissatisfaction with the push-to-advance methodology. Catheters have been adorned with a wide assortment of spiral and threaded features described as intended to ease the trauma and pain of what clearly remained a push-in device. Alvord's U.S. Pat. No. 207,932 (US), Peyret's 564,832 (French), Hayes' U.S. Pat. No. 1,644,919 (US), and Jacoby's U.S. Pat. No. 1,888,349 (US) are representative of these. In all cases, these disclosures fail to recognize that the basic push technique is fundamentally flawed and should be abandoned, and fail to resolve the critical features of structure necessary for rotational advancement as a substitute for the push method.
Other art reveals the use of spiral features for different purposes. For example, Spinosa's U.S. Pat. No. 3,815,608 (US), discloses a catheter with a thread designed to hold the urethral wall away from the shaft to allow urine to flow around the outside of the catheter. These disclosures likewise reveal a reliance on push-in methods or an assumption that such structures can be pulled out without regard to the spiral features, again failing to recognize rotation as a viable substitute for push, and failing to resolve the critical features of structure necessary for effective rotational advancement.
As a further indication of the failure of prior art similar to the above inventions to provide effective improvements to push-in methods, there is no apparent indication among the products commercially available, or in the medical practices known to the applicant, that any of these spirally ornamented devices were ever found to be viable.
Gastrointestinal Endoscopes
The current device used for inspection and treatment of the GI (gastrointestinal) tract is a flexible Endoscope. This device takes a high level of skill to use, is difficult to maneuver and can be very painful for the patient, due to the basic push-to-advance design that has not changed since the device was invented in the early 1960s. The distal tip of the endoscope has the following parts:                1. a channel opening for suction and passage of accessories,        2. the light guide lens to distribute light from the fiberoptic bundle to illuminate the visual field,        3. the objective lens to focus an image of the mucosa onto the face of the image bundle and transmit it back to the eye piece,        4. an air/water jet, which supplies air to inflate the organ being observed, and water to clean off the image lens.        
The Bending Section is the distal end of the tube, ranging from approx. 8-15 cm long, which can articulate to steer the scope as it is pushed inward and is controlled by a cable mechanism that is connected to control knobs on the proximal handle.
The Insertion Tube, which makes up the rest of the 60-150 cm length, is not capable of controlled deflection. It has a tailored bending flexibility and torque transmission which is of major importance in endoscope design. Most instruments have two-stage bending stiffness, i.e., the distal portion of the insertion tube is more flexible than the proximal portion. The Flexibility of each portion of the insertion tube requires extensive clinical testing to ensure that the endoscope handles easily and produces a minimum of patient discomfort.
The colon is a tubular organ which runs from the cecum in the right lower quadrant to the rectum. It is widest in the cecum and ascending colon and gradually narrows as one approaches the rectum. The colon is divided into the following sections:
a. the cecum; the ascending colon, which runs cephalad (towards the head) from the cecum to the hepatic flexure;
b. the transverse colon, which runs from the hepatic flexure in the upper quadrant of the splenic flexure in the left upper quadrant;
c. the descending colon, which runs caudad (toward the feet) from the splenic flexure to the left lower quadrant;
d. the sigmoid colon, which runs from the left lower quadrant to the rectosigmoid junction; and
e. the rectum, which extends down to the anal canal.
The inner layer of circular muscle is present throughout the colon. The outer longitudinal muscle in the wall of the colon is fused into three bands, the teniae coli. These bands start at the base of the appendix and run in the wall of the colon down to the rectum where they diffuse into the muscular coat. The three teniae cause the colon to have a triangular appearance endoscopically; this is especially prominent in the ascending and transverse colon. The haustra are outpouchings of the colon, separated by folds. In the descending colon the endoscopic appearance is often tubular.
Most experienced colonoscopists use similar endoscopic techniques. Air is introduced to inflate the colon, but as little as possible to prevent overdistension. The pressure on the device is gentle to avoid stretching the colonic wall or mesentery (the connective tissue that holds the colon like a fan) which can cause pain, a vagal episode, or a perforation. The lumen is kept in view at all times; little or none of the examination is performed blindly, because you are pushing a stiff instrument
A variety of in and out maneuvers are used to “accordian” the colon on the colonoscope, keeping the colonoscope free of loops as possible. In the difficult colon, special maneuvers such as the creating of an alpha loop in the sigmoid colon are used to pass the sharply angulated sigmoid/descending colon junction. This maneuver may require fluoroscopic guidance and training in the technique.
The colonoscope is advanced to the cecum under direct vision. The detailed examination of the mucosa is usually performed as the colonoscope is slowly removed from the cecum.
To inspect the whole length of the large intestine requires a highly skilled practitioner, which makes the procedure costly. Even still the procedure can be very painful for the patient, making sedation necessary. This is due to the inherent deficiencies in the “push-to-advance” design.
In summary, there are problems in making present push-in catheters, dilators, and occluders stiff enough for penetration and flexible enough to make the turns without undue risk of trauma to the wall of the passageway when being pushed in; and once installed, comfortable enough to wear for an extended period. The problems with stent encrustation and removal are well known. Self-administration is inhibited by all of the short-comings of the prior art. Further injury, infection and discomfort can result from unskilled or improper technique. The problems with colonoscopy have been previously described.
The long history of push-in catheters/dilators and occluders has gradually crystallized into an industry wide, self-perpetuating, fundamental assumption that catheters are to be mainly pushed through bodily passageways, albeit with some rotational easing. This “fact” is so widely perpetuated and pervasive in the commercially available products and medical practices as to have stifled original thinking in this art. This, in spite of it's well-recorded short comings of pain, trauma, risk of rupture, and failed, aborted or incomplete procedures and need for skilled practitioners and special equipment for monitoring and safeguarding against the inherent problems.